This application is a revision of one (ROl HS07019) submitted February 1 1991. We will assess compliance with NIH Consensus Conference guidelines on early stage breast cancer employing prospective data from a representative sample of 1400 Massachusetts women with newly diagnosed disease. Cases will be identified through hospital pathology records and data will be collected. through chart review, physician questionnaires, and patient interviews. We will determine the proportion of women who fail to receive care that complies with consensus guidelines. Rates of compliance with longstanding recommendations will be compared with rates for recently promulgated recommendations. We will identify patient (e.g. age, race, socio-economic status), physician (e.g. age, specialty, gender) and hospital (e.g. size, location, teaching status) factors associated with care that does not comply with guidelines. We will also determine the degree to which special medical circumstances, patient preferences, lack of physician knowledge and physician disagreement with guidelines account for non-compliance with guidelines. The results of our analyses will allow us to propose targeted interventions aimed at increasing compliance with guidelines.